The present invention relates to a plastic molded semiconductor package and a method for producing the same, and more particularly relates to improvement in production of a plastic molded semiconductor package provided with a heat sink for dissipation of heat.
One typical example of a multi-layer molded plastic package of such a type is proposed in Japanese Patent Opening Sho. 63-246851 originated from a U.S. patent application Ser. No. 2144 filed on Jan. 12, 1987. The molded plastic package of this prior art includes metallic power source and earth planes super-imposed with each other. The earth plane is arranged on the power source plane and provided with a center opening for attachment of a semiconductor die directly on the power source plane. The power source and earth planes are bonded to each other by an electrically insulating sheet covered with polyimide adhesive. The top surface of the earth plane is also locally covered with another electrically insulating sheet covered with polyimide adhesive for attachment of leads. The semiconductor die is provided on its top surface with a plurality of source terminal and earth terminal pads. After attachment of the semiconductor die onto the power source plane past the center opening of the earth plane, the power source terminal pads on the semiconductor die are connected via bond wires to the power source and the earth terminal pads are connected to the earth plane.
Thanks to use of the power source and earth planes, it is no longer to connect the power source terminal pads and earth terminal pads to power source leads and earth leads. The construction of the semiconductor package can be made very compact and the mutual-inductance between the leads can be reduced significantly.
Despite such advantages, however, the multi-layer construction of this semiconductor package entails increased number of operational steps in production, thereby causing undesirable rise in production cost.